For a silver halide photographic light-sensitive material which records optical information, it is an important function to reproduce optical information specially with a high fidelity.
The light incident upon a light-sensitive material travels in the light-sensitive material while spreading specially, and this spreading of light hinders faithful reproduction of optical information. The spreading of light is attributable, for example, to 1. scattering at the interface between photographic structural layers consisting of various hydrophilic colloids or the interface between said photographic structural layer and a support, 2. scattering caused not only by solid particles such as silver halide particles and matting agent particles but by oil droplets, respectively contained in photographic structural layers consisting of various hydrophilic colloids and 3. scattering due to a support.
In recent years, there have come to be used paper supports covered on both sides with a resin such as polyolefin, as the support for silver halide photographic light-sensitive materials in view of rapid processing. In these supports, a white pigment such as titanium dioxide is usually dispersed in the resin layer on the side to be coated with an emulsion layer. But the content of such a white pigment dispersed in the resin is limited to a certain level in respect of dispersion stability. For titanium dioxide, the upper limit of the content is usually about 15 wt %. But a content of this level is not sufficient in providing a good covering power; therefore, a portion of the light incident upon a light-sensitive material passes through the resin layer and diffuses into a paper substrate. A portion of the diffusing light returns again, repassing through the resin layer, to photographic structural layers consisting of hydrophilic colloids and exposes silver halide grains. As a result, obscurity or bleeding is caused in images, deteriorating the sharpness of images heavily. It is known in the art a technique to prevent the diffusion of light in a paper substrate by providing a hydrophilic colloid layer containing a dye or colloidal silver, which reduces the quantity of light coming into the paper substrate by absorbing the light which has passed through a photographic emulsion layer, between the photographic emulsion layer and the support. The layer provided between a photographic emulsion layer and a support for such a purpose is called an antihalation layer and described, for example, on pages 53-54 of Research Disclosure Vol. 175, Item 17559 (Nov. 1978) and on pages 649-650 of Research Disclosure Vol. 187, Item 18716 (Nov. 1979).
Further, with the increasing tendency toward high quality printed matters, the requirement of sharpness in processes of artworking, photographing and contact printing is getting more and more severe. That is to say, there has come to be strongly demanded the foregoing faithful reproduction of optical information free from obscurity and bleeding in images.
To color the antihalation layer, there are usually contained therein water-soluble dyes such as oxonol dyes having a pyrazolone nucleus or barbituric acid nucleus and described in British Pat. Nos. 506,385, 1,177,429, 1,311,884, 1,338,799, 1,385,371, 1,467,214, 1,433,102, 1,553,516, Japanese Pat. O.P.I. Pub. Nos. 85,130/1973, 14,420/1974, 161,233/1980, 111,640/1984 and U.S. Pat. Nos. 3,247,127, 3,469,985, 4,078,933; and oxonol dyes having a hydroxypyridone nucleus and described in British Pat. Nos. 1,278,621, 1,512,863, 1,521,083 and 1,579,899. These water-soluble dyes, however, are liable to lower the sensitivity and to cause fogging in a photographic emulsion layer. Some of them produce undesirable coloring on photographic images obtained by rapid processing which becomes practiced in recent years. Further, providing an antihalation layer lowers the white brightness of a paper support, this weakens the whiteness required of finished photographs and darkens images thereof.